Call control method for dual-mode mobile terminals and a dual-mode mobile terminal using the same

ABSTRACT

A dual-mode mobile terminal, which can access synchronous and asynchronous mobile communication systems, includes a key input panel and a controller. The key input panel includes a call switching key for switching between calls from the two systems and a call end key for ending calls from the two systems. While the terminal performs communication of one call received from one of the two systems in a general communication mode over a communication channel currently established by the one system, the controller determines whether an incoming call is received from the other system. If the incoming call is received, the controller notifies the user of receipt of the incoming call. If the call switching key is pressed, the controller prepares a communication environment for communication of the incoming call, allowing the user to perform the communication of the incoming call while maintaining the currently established communication channel.

PRIORITY

This application is a continuation application of U.S. patentapplication Ser. No. 10/929,259, filed on Aug. 30, 2004, and claimspriority to an application entitled “CALL CONTROL METHOD FOR DUAL-MODEMOBILE TERMINALS AND DUAL-MODE MOBILE TERMINAL USING THE SAME”, filed inthe Korean Intellectual Property Office on Jan. 14, 2004 and assignedSer. No. 2004-0002662, the contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a mobile terminal, and moreparticularly to a dual-mode mobile terminal that supports bothsynchronous and asynchronous modes.

2. Description of the Related Art

The use of mobile terminals has been rapidly increasing around theworld. Mobile communication systems, which provide communicationservices to the mobile terminals, can be mainly divided into a GSMmobile communication system that is primarily used in Europe and a CDMAmobile communication system that is primarily used in North America. TheCDMA mobile communication system employs a synchronous data transmissionmode and the GSM mobile communication system employs an asynchronousdata transmission mode. The synchronous mode achieves synchronizationbetween a transmitter and a receiver using a GPS satellite signal,whereas the asynchronous mode achieves the synchronization using aspecial chip or software.

In some areas, both the synchronous CDMA mobile communication system andthe asynchronous GSM mobile communication system provide overlappingmobile communication services. In such areas where the CDMA and GSMmobile communication systems are used together, users need to have CDMAterminals if they wish to receive CDMA services or GSM terminals if theywish to receive GSM services. Dual-mode mobile terminals, which canaccess both the synchronous CDMA and asynchronous GSM mobilecommunication systems to receive communication services therefrom, areunder development to meet this need.

The dual-mode mobile terminal generally operates in one of thesynchronous and asynchronous communication modes, and switches betweenthe synchronous and asynchronous communication modes according to userselection.

Another dual-mode mobile terminal, which can access both the synchronousCDMA and asynchronous GSM mobile communication systems and operate inthe synchronous and asynchronous communication modes at the same time,is also under development.

Although dual mode terminals are known in the art, there has beensuggested no method or technology for controlling calls in the dual-modemobile terminals, which can operate in the synchronous and asynchronouscommunication modes simultaneously, when the terminal receives callsfrom both the CDMA and GSM mobile communication systems at the sametime.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide a callcontrol method for mobile terminals and a mobile terminal using themethod.

In accordance with the present invention, the above and other objectscan be accomplished by the provision of a dual-mode mobile terminalcapable of accessing a synchronous mobile communication system and anasynchronous mobile communication system, the terminal including a keyinput unit including a call switching key for switching between a callfrom the synchronous mobile communication system and a call from theasynchronous mobile communication system and a call end key for endingcalls from the mobile communication systems; and a controller fordetermining, during a communication of one call received from one of thesynchronous and asynchronous mobile communication systems in a generalcommunication mode, whether another call is received from the othermobile communication system, and notifying a user of the terminal of thereceipt of the other call if it is determined that the other call hasbeen received from the other mobile communication system, and preparinga communication environment for communication of the other call if thecall switching key is pressed by the user to allow the user to performthe communication of the other call while maintaining a communicationchannel that has been established for the communication of the one call.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a diagram showing service areas of mobile communicationsystems that can be accessed by a dual-mode mobile terminal according tothe present invention;

FIG. 2 is a block diagram showing the configuration of a dual-modemobile terminal according to an embodiment of the present invention;

FIGS. 3A and 3B are diagrams showing in detail the configuration offirst and second switches provided in the dual-mode mobile terminal ofFIG. 2, respectively;

FIG. 4 is a control flow diagram showing how call control is performedin the dual-mode terminal according to an embodiment of the presentinvention; and

FIG. 5 is an example of a screen of a display unit when call control isperformed in the dual-mode terminal according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention will now be describedin detail with reference to the annexed drawings. In the followingdescription, a detailed description of known functions andconfigurations incorporated herein will be omitted when it may make thesubject matter of the present invention unclear.

FIG. 1 is a diagram showing service areas of mobile communicationsystems that can be accessed by a dual-mode mobile terminal according tothe present invention. A dual-mode mobile terminal 100 is positioned ina service area covered by both a synchronous mobile communication system10 and an asynchronous mobile communication system 20. In the presentinvention, it is assumed that the dual-mode terminal 100 cansimultaneously gain access to synchronous and asynchronous communicationsystems and receive communication services therefrom. Specifically, thedual-mode terminal 100 can receive calls from the synchronous andasynchronous communication systems 10 and 20. The dual-mode terminal 100can also receive SMS messages and various other information from thesynchronous and asynchronous mobile communication systems 10 and 20 atthe same time. The user of the dual-mode terminal 100 can select adesired one of the synchronous and asynchronous communication systems 10and 20 and transmit a call to the selected system.

In the present invention, while the dual-mode terminal 100 performs thecommunication of a call received from one of the synchronous CDMA andasynchronous GSM communication systems, if the terminal 100 receives anincoming call from the other system, the terminal 100 notifies the userof the receipt of the incoming call from the other system. When the useris notified of the receipt of the incoming call, the user can then pressa call end key or a call switching key. The call end key may be embodiedas a call end key for ending a call from the asynchronous mobilecommunication system and a call end key for ending a call from thesynchronous mobile communication system. The call switching key allowsthe user to suspend current communication of a call received from one ofthe synchronous and asynchronous communication systems and then torespond to another call received from the other system.

According to the present invention, the dual-mode terminal 100determines whether the user has pressed the call end key or the callswitching key, and then performs an operation corresponding to thepressed key. If a call end key is pressed, the dual-mode terminal 100ends a call received from a mobile communication system (for example,one of the asynchronous and synchronous mobile communication systems)corresponding to the pressed call end key, and transmits a call endmessage to the mobile communication system. On the other hand, if thecall switching key is pressed, the dual-mode terminal 100 suspendscurrent communication of one call and prepares a communicationenvironment for communication of another call by controlling a speakerand a microphone while maintaining a communication channel that has beenestablished for the current communication. The configuration of such adual-mode terminal will now be described with reference to FIG. 2.

As shown in FIG. 2, the dual-mode terminal 100 includes a synchronousCDMA module 2, an asynchronous GSM module 4, a controller 30, a displayunit 40 and a key input unit 42. The dual-mode terminal 100 furtherincludes a microphone 50, a speaker 60 and first and second switches 52and 62 connected respectively to the microphone 50 and the speaker 60.The first and second switches 52 and 62 respectively, are controlled bycontrol signals from the controller 30.

The controller 30 controls the overall operation of the synchronous CDMAmodule 2 and the asynchronous GSM module 4. The synchronous CDMA module2 includes a CDMA antenna 11, a transmission/reception separator 12, areceiver 14, a transmitter 16 and a CDMA modem 18. The CDMA antenna 11is used to transmit and receive radio signals to and from thesynchronous CDMA mobile communication network 10 (FIG. 1), and isdesigned to be sensitive to frequencies used in the CDMA mobilecommunication network. If a radio signal is received from the CDMAmobile communication network 10 through the CDMA antenna 11, thereceived signal is input to the transmission/reception separator 12 inthe CDMA module 2. The transmission/reception separator 12 in the CDMAmodule 2 outputs the received signal from the CDMA antenna 11 to thereceiver 14. When the transmission/reception separator 12 receives atransmission signal from the CDMA modem 18 via the transmitter 16, theseparator 12 outputs the transmission signal to the CDMA antenna 11. Thetransmitter 16 modulates data output from the CDMA modem 18, andtransmits an RF signal carrying the modulated data through thetransmission/reception separator 12 and the CDMA antenna 11. Thereceiver 14 receives a radio signal through the CDMA antenna 11 via thetransmission/reception separator 12 and converts the received signalinto an intermediate frequency (IF) signal and demodulates it into data,and then outputs it to the CDMA modem 18. The CDMA modem 18 modulates anaudio signal received through the microphone 50 via a first switch 52into a radio signal, and demodulates a radio signal received through thereceiver 14 into an audio signal and outputs it via a second switch 62through the speaker 60.

The asynchronous GSM module 4 includes a GSM antenna 21, a switch 22, areceiver 24, a transmitter 26 and a GSM modem 28. The GSM antenna 21 isused to transmit and receive radio signals to and from the asynchronousGSM mobile communication network 20 (FIG. 2), and is designed to besensitive to frequencies used in the GSM mobile communication network.If a radio signal is received from the GSM mobile communication network20 through the GSM antenna 21, the received signal is input to theswitch 22 in the GSM module 4. The switch 22 in the GSM module 4 outputsthe received signal from the GSM antenna 21 to the receiver 24. When theswitch 22 receives a transmission signal from the GSM modem 28 via thetransmitter 26, the switch 22 outputs the transmission signal to the GSMantenna 21. The GSM system uses a Time Division Duplex (TDD) scheme,such that channels assigned to uplink and downlink are spaced apart fromeach other by specified time intervals. In the GSM system, a terminaland a base station perform transmission and reception in intervals oftime slots so that transmission and reception are not performed in theterminal at the same time.

That is, the GSM terminal deactivates its receiver during transmissionand deactivates its transmitter during reception. The switch 22 connectsan output of the transmitter 26 to the GSM antenna 21 duringtransmission under the control of the controller 30. On the other hand,the switch 22 connects the GSM antenna 21 to an input of the receiver 24during reception under the control of the controller 30.

The transmitter 26 modulates data output from the GSM modem 28 andtransmits an RF signal carrying the modulated data through the switch 22and the GSM antenna 21. The receiver 24 receives a radio signal throughthe GSM antenna 21 via the switch 22, and converts the received signalinto an intermediate frequency signal and demodulates it into data, andthen outputs it to the GSM modem 28. The GSM modem 28 modulates an audiosignal received through the microphone 50 via a first switch 52 into aradio signal, and demodulates a radio signal received through thereceiver 24 into an audio signal and outputs it via a second switch 62through the speaker 60.

The display unit 40 generally includes a Liquid Crystal Display (LCD) todisplay various messages, icons and the like under the control of thecontroller 30. The key input unit 42 includes various keys includingnumber keys to provide key input data corresponding to a key entered bythe user to the controller 30. According to the present invention, thekey input unit 42 may further include a call switching key, a call endkey for ending a call received from the asynchronous mobilecommunication system and a call end key for ending a call received fromthe synchronous mobile communication system. The CDMA antenna 11 and theGSM antenna 21 may also be embodied as a single antenna.

The controller 30 is connected to the synchronous CDMA module 2 and theasynchronous GSM module 4 to control the overall operation of the twomodules 2 and 4. Specifically, the controller 30 allows radio signals tobe received and transmitted through the synchronous CDMA module 2 andthe asynchronous GSM module 4.

When a call is received through the synchronous CDMA module 2 or theasynchronous GSM module 4, the controller informs the user of thereceipt of the call. If the user responds to the received call, thecontroller 30 controls the first and second switches 52 and 62 connectedrespectively to the microphone 50 and the speaker 60 so that themicrophone 50 and the speaker 60 are connected to the synchronous CDMAmodule 2 or to the asynchronous GSM module 4 through which the call isreceived. Specifically, as shown in FIG. 3A, the controller 30 applies amicrophone control signal to the first switch 52 so that the microphone50 is connected to one of the CDMA and GSM modems 18 and 28. Inaddition, as shown in FIG. 3B, the controller 30 applies a speakercontrol signal to the second switch 62 so that the speaker 60 isconnected to one of the CDMA and GSM modems 18 and 28, respectively.

While the user performs a communication via one of the synchronous andasynchronous mobile communication systems with which the terminal 100has been connected through a corresponding one of the synchronous CDMAmodule 2 and the asynchronous GSM module 4, if the terminal 100 receivesan incoming call from the other mobile communication system, thecontroller 30 notifies the user of the receipt of the incoming calltherefrom. For this notification, the controller 30 may display apredetermined message or icon on the display unit 40 or output an alertor alarm sound. The controller 30 then determines whether the call endkey or the call switching key is pressed by the user. If the call endkey is pressed, the controller 30 ends a call received from one of thesynchronous and asynchronous mobile communication systems correspondingto the pressed call end key, and transmits a call end message to thatparticular mobile communication system. The controller 30 then controlsthe first and second switches 52 and 62 so that the microphone 50 andthe speaker 60 are connected to one of the CDMA and GSM modems 18 and 28corresponding to the other of the synchronous and asynchronous mobilecommunication systems, a call from which has been maintained, therebyallowing the user to perform communication of the call that has beenmaintained.

On the other hand, if the call switching key is pressed, the controller30 controls the first and second switches 52 and 62 so that the speaker50 and the microphone 60, which have been connected to one of the CDMAand GSM modems 18 and 28 for current communication of a call receivedthrough the one modem, are connected to the other modem to allow theuser to perform communication of another call received through the othermodem while maintaining a communication channel established for thecurrent communication.

A description will now be given of how call control is performed in thedual-mode mobile terminal with reference to FIG. 4.

As shown in FIG. 4, the controller 30 in the dual-mode terminal is in ageneral communication mode at step 210, in which the dual-mode terminalperforms a general communication function in response to an incomingcall from one of the synchronous and asynchronous mobile communicationsystems. While the dual-mode terminal performs current communication ofthe call received from one mobile communication system in the generalcommunication mode, the controller 30 determines at step 220 whether anincoming call is received from the other communication system (i.e., amobile communication system other than the one mobile communicationsystem with which the current communication has been established). If noincoming call is received from the other mobile communication system,the controller 30 allows the terminal to operate in the generalcommunication mode. On the other hand, if an incoming call is receivedfrom the other mobile communication system, the controller 30 moves tostep 230 to notify the user of the receipt of the incoming call from theother mobile communication system. For example, the controller 30notifies the user of the receipt of the different call via a message asshown in FIG. 5. In other words, the controller 30 displays the messageas shown in FIG. 5 indicating the receipt of the incoming call from theother mobile communication. Here, the controller 30 may also display acalling telephone number and a received time of the incoming call,together with the message indicating the receipt of the incoming call.

The controller 30 then determines at step 240 whether the user haspressed a key on the key input unit 42. If the user has pressed a key,the controller 30 moves to step 250 to determine whether the pressed keyis a call switching key or a call end key. As shown in FIG. 5, thecontroller 30 provides, for example, three key options (i.e., a callswitching key 310, a key 320 for ending a call received from theasynchronous GSM mobile communication system and a key 330 for ending acall received from the synchronous CDMA mobile communication system) tothe user so that the user selects a desired key from the three keys 310,320 and 330. The user selects the call switching key 310 in order toperform a communication while maintaining a call from the synchronousmobile communication system and a call from the asynchronous mobilecommunication system. On the other hand, the user selects one of the twocall end keys 320 and 330 in order to end one of the calls from thesynchronous and asynchronous mobile communication systems and thenperform communication in a general communication mode. In the example ofFIG. 5, the two keys 320 and 330 are provided to end the calls from thesynchronous and asynchronous mobile communication systems, respectively.Alternatively, only one call end key may be provided to end a call fromeither of the two mobile communication systems. In this case, if theuser has pressed the call end key, the controller 30 may control thefirst and second switches 52 and 62 to terminate current communicationperformed through one of the CDMA and GSM modems 18 and 28, to which themicrophone 50 and the speaker 60 have been connected by the first andsecond switches 52 and 62.

Referring to FIG. 4, if the user has pressed a call end key, thecontroller 30 moves to step 270 to end a call from a mobilecommunication system (for example, one of the asynchronous andsynchronous mobile communication systems) corresponding to the pressedcall end key by transmitting a call end message to that mobilecommunication system. The controller 30 then moves to step 280 toprepare a communication environment for communication of the call thathas not been ended. That is, the controller 30 controls the first andsecond switches 52 and 62 so that the microphone 50 and the speaker 60are connected to a modem for one of the two mobile communicationsystems, a call from which has been maintained, thereby allowing theuser to perform communication for the call. The controller 30 thenreturns to step 210 to enter the general communication mode.

If the call switching key has been pressed, the controller 30 moves tostep 260 to control the first and second switches 52 and 62 so that thespeaker 50 and the microphone 60, which have been connected to one ofthe CDMA and GSM modems 18 and 28 for the current communication of acall received through the one modem, are connected to the other modemwhile maintaining the communication channel established for the currentcommunication. This allows the user to perform communication of anothercall received through the other modem while maintaining thecommunication channel established for the current communication. Thecontroller 30 then returns to step 240.

As apparent from the above description, the present invention provides acall control method for dual-mode mobile terminals and a dual-modemobile terminal using the method, whereby the user can receive both acall from a synchronous mobile communication system and a call from anasynchronous mobile communication system, and even when two incomingcalls are received simultaneously from two different mobilecommunication systems, the user can perform communication in response tothe two incoming calls.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims. Accordingly, the scope of thepresent invention should not be limited to the above embodiments, butdefined by the accompanying claims as well as equivalents thereof.

1. A dual-mode mobile terminal capable of simultaneously accessingcommunication systems using different types of networks, the terminalcomprising: a key input unit including a key which is used for switchingbetween a first call from a first mobile communication system and asecond call from a second mobile communication system; a controller fordetermining, whether the second call is received from the second mobilecommunication system while the first call of the first mobilecommunication system is currently connected, notifying a user of theterminal of the reception of the second call from the second mobilecommunication system when it is determined that the second call has beenreceived from the second mobile communication system, and enabling acommunication environment to perform communication of the receivedsecond call while maintaining the first mobile communication channelthat is currently connected when the key is pressed by the user; a firstmodem for the first mobile communication system; a second modem for thesecond mobile communication system; a first switch connected to amicrophone for switching the microphone between the first and secondmodems; and a second switch connected to a speaker for switching thespeaker between the first and second modems, wherein the controllercontrols the first and second switches so that the microphone and thespeaker are connected to one of the first and second modemscorresponding to one of the mobile communication systems.
 2. Theterminal as claimed in claim 1, wherein the first mobile communicationsystem includes an asynchronous mobile communication system, and thesecond mobile communication system includes a synchronous mobilecommunication system.
 3. The terminal as claimed in claim 1, wherein thefirst mobile communication system includes a synchronous mobilecommunication system, and the second mobile communication systemincludes an asynchronous mobile communication system.
 4. The terminal asclaimed in claim 2, wherein the key input unit further comprises: a callend key for ending the second call from the second mobile communicationsystem, wherein when the first call from the first mobile communicationsystem is on hold and the call end keys is pressed, the controller endsthe second call from the second mobile communication system and preparesa communication environment for the first mobile communication system ofthe first call which is on hold.
 5. The terminal as claimed in claim 4,wherein when the call of each mobile communication system ends by aninput of the call end key, an end message is sent.
 6. The terminal asclaimed in claim 1, wherein the controller displays a message indicatingthat the second call been received on a display unit while the firstcall of the first mobile communication system is currently connected,thereby notifying the user of reception of the second call.
 7. Theterminal as claimed in claim 1, wherein when receiving the second callfrom the second communication network while the terminal is currently incommunication with the first communication network, the controllernotifies the reception of the second call by an alert or an alarm sound.8. A dual-mode mobile terminal capable of simultaneously accessingcommunication systems using different types of networks, the terminalcomprising: a key input unit including a key which is used for switchingbetween a first call from a first mobile communication system and asecond call from a second mobile communication system; a first modem forthe first mobile communication system; a second modem for the secondmobile communication system; a first switch connected to a microphonefor switching the microphone between the first and second modems; asecond switch connected to a speaker for switching the speaker betweenthe first and second modems; a controller for determining, whether thesecond call is received from the second mobile communication systemwhile the first call of the first mobile communication system iscurrently connected, notifying a user of the terminal of the receptionof the second call from the second mobile communication system when itis determined that the second call has been received from the secondmobile communication system, and controlling the first and secondswitches so that the user performs communication with the receivedsecond call while maintaining a communication channel that is currentlyconnected when the key is pressed by the user; a first antenna forreceiving a first signal from the first mobile communication system; anda second antenna for receiving a second signal from the second mobilecommunication system.
 9. A method for processing a call in a dual-modemobile terminal which can simultaneously access mobile communicationsystems using different types of networks, and has a key for switchingbetween a first call from a first mobile communication system and asecond call from a second mobile communication system, the methodcomprising the steps of: determining whether the second call is receivedfrom the second mobile communication system while the first call of thefirst mobile communication system is currently connected; notifying auser of the terminal of the reception of the second call from the secondmobile communication system when it is determined that the second callhas been received from the second mobile communication system; enablingthe user to perform communication of the received second call whilemaintaining a communication channel that is currently connected when thekey is pressed by the user, or ending communication when a call end keyis pressed by the user; switching a first switch and a second switchaccording to an input of the call end key and the key, the first switchbeing connected to a microphone for switching the microphone between afirst modem for the asynchronous mobile communication and a second modemfor the synchronous mobile communication, the second switch beingconnected to a speaker for switching the speaker between the first modemfor the asynchronous mobile communication and the second modem for thesynchronous mobile communication; and controlling the first and secondswitches so that the microphone and the speaker are connected to one ofthe first and second modems corresponding to one of the mobilecommunication systems.
 10. The method as claimed in claim 9, wherein thefirst mobile communication system includes an asynchronous mobilecommunication system, and the second mobile communication systemincludes a synchronous mobile communication system.
 11. The method asclaimed in claim 9, further comprising a step of sending an end messagewhen the call of the mobile communication systems ends according to aninput of the call end key.
 12. The method as claimed in claim 10,further comprising the steps of: determining whether a call end key forending a second call from the synchronous mobile communication system isinputted from a key input unit or a call end key for ending a first callfrom the asynchronous mobile communication system is inputted from thekey input unit; and when any one of the call end keys is pressed, endingthe current call of a mobile communication system corresponding to thepressed call end key, and preparing a communication environment for ahold call which still connected.
 13. The method as claimed in claim 9,wherein the controller displays a message indicating that the receivedsecond call has been received on a display unit, thereby notifying theuser of reception of the second call.
 14. The method as claimed in claim9, wherein when receiving the second call from the second communicationnetwork while the terminal is currently in communication with the firstcommunication network, the controller notifies the reception of thesecond call by an alert or an alarm sound.
 15. A method for processing acall in a dual-mode mobile terminal which can simultaneously accessmobile communication systems using different types of networks, themethod comprising the steps of: determining, whether there is a secondsignal received through a second antenna which receives a second signalof a second mobile communication system while a first signal of a firstmobile communication system being currently in communication connectionthrough a first antenna; notifying a user of the terminal of receptionof a second call from the second mobile communication system when thesecond call from the second mobile communication system has beenreceived; receiving, from the user, either a key for switching between afirst call from the first mobile communication system and the secondcall from the second mobile communication system, or an end key forending the either calls; and when the key is pressed by the user,switching a first switch and a second switch, the first switch beingconnected to a microphone for switching the microphone between a firstmodem for communication with the first mobile communication system and asecond modem for communication with the second mobile communicationsystem, and the second switch being connected to a speaker for switchingthe speaker between the first modem and the second modem, so that theuser performs communication with the second call of the second mobilecommunication system while maintaining a communication channel that iscurrently connected via the first mobile communication system.